HAVING established the principle of temperamental influence, and having indicated how the different hormones reinforce and modify neural function, we must return once more to a consideration of the latter. It is however necessary to change our point of view, though, in passing from the consideration of bodily function to that of mental function we do not alter the subject of study, but only the aspect from which we study it. Heretofore we have been chiefly concerned with the more lowly organized patterns, whose physical aspect was presented for our study, but whose psychical aspect was of such a low order of organization that it failed to have significance. We might continue to attempt to follow the engraphic physical structure of the more complex mental patterns, together with the temperamental factors which influence their function, but this would lead us into such a complicated maze of neurones that our efforts would be fruitless; especially as the exact function of the higher cerebral realms, such as the frontal lobes, are still beyond our grasp. For this reason, it is more useful to concentrate on the psychical aspect, and transfer our attention from physiology to psychology. This is the more important, inasmuch as at these higher levels it is the psychological and not the physiological aspect which is significant; and in order to be intelligible, it is necessary to describe and examine behaviour according to psychological laws. In this sense it is legitimate to talk of an animal being guided by instinct, or by reason. This does not mean that we regard instinct or reason as having any force or influence of themselves. All that is implied is that the behaviour of the animal is a function of the activation of that engraphic pattern, which involves instinct or reason, and which is significant in virtue of that instinct or reason. At these higher “mental” levels, the organization of the

engram involves both central and visceral systems, on the afferent and efferent sides, and hence we can always recognize three phases in the processes under discussion. These are an afferent phase or cognition, involving the mental aspect of the reception of the incoming stimuli; a visceral phase or affect, involving pleasure or unpleasure; and an efferent phase or conation involving the mental aspect of the urge or “wish” * towards activity. These phases of cognition, affect, and conation are always present in every mental process, but may be differently stressed, and occur in different proportions.